The special envoy, a five-term lawmaker of the Democratic Party, said that Japan and South Korea share not just a market economy and democracy but also the threats posed by North Korea's nuclear and missile ambitions.
During a phone call with Chinese President Xi Jinping last week, South Korea's new president, Moon Jae-in, said he was aware of Chinese worries about THAAD and asked Xi to help resolve difficulties facing South Korean businesses operating in China.
A liberal democrat who lost narrowly to now impeached President Park Geun-hye in 2012, analysts say Moon has an opportunity to draw a line under his predecessor's damaged relations with Beijing and start afresh.
In their meeting at the Blue House, the presidential palace, the two sides followed up on a recent telephone conversation between President Moon Jae-in and Trump, who agreed to hold a summit meeting in Washington next month.
Moon Hee-sang later met with Chief Cabinet Secretary Yoshihide Suga to discuss the North Korean situation. "But THAAD is still the most critical barrier for the relationship to go forward".
China's top diplomat on Thursday reiterated calls for its dismantling.
Japan believes that a 2015 accord inked between Tokyo and Seoul and the paying of 1 billion yen (8.98 million USA dollars) past year to a South Korean fund to help former comfort women and their families as part of the deal would settle the matter.
Zhao said this was likely meant to force Moon's hand. The move sparked protests in South Korea, with some citizens claiming the system could provoke the North to strike.
Beijing vehemently opposes the missile shield, saying its powerful radar will allow it to monitor missile launches, aircraft flights and other sensitive activities in northeastern China.More news: Madrid Open: Nadal top Goffin to reach semis
Adam Cathcart, an expert on China and Korea at the University of Leeds, said Beijing "has really backed itself into a corner on the THAAD issue, having made it an explicit red line issue for the Chinese public".
"China can be more flexible", Zhao said.
While FireEye researcher John Miller, too, said United States and European security officials maintain it was too early to say who is behind the attack, they did not rule out North Korea as a suspect.
North Korea conducted two nuclear tests a year ago, which are likely to have improved its know-how in making nuclear weapons small enough to fit on long-range missiles.
In what both governments hoped was a major step forward, the two countries had agreed in 2015 to a deal created to end a row over Korean "comfort women" forced into sex slavery for Japanese soldiers during the World War II.
Whereas Soviet nuclear weapons in Cuba posed an immediate threat that required a quick and decisive response, North Korea remains unable to launch a direct nuclear attack against the United States with its current arsenal, allowing the U.S. to continue its slow-burning strategy of "strategic patience" despite a recent spike in tensions.Pyongyang's latest missile test, however, indicates that North Korea is making significant progress towards obtaining a nuclear weapon able to strike the USA mainland.
MCST said the deals are a result of efforts to diversify target markets for Korean culture contents due to the ongoing ban of TV and entertainment shows in China, which is Korea's biggest importer of such content.
Abe said the early dispatch to Tokyo from Seoul of the special envoy after President Moon established his administration was a sign of cordial relations between both countries.
But he has said the North must change its attitude of insisting on pressing ahead with its arms development before dialogue is possible.